Automatic photographic sound-reproducing mechanism



April 28, 1931. 5 FOREST 1,802,595

AUTOMATIC PHOTOGRAPHIC SOUND REPRODUCING MECHANISM Filed Feb. 18, 1928 2 Sheets-Sheet 1 H II April 28, 1931. DE FOREST 1,802,595

, AUTOMATIC PHOTOGRAPHIC SOUND REPRODUCING MECHANISM Filed Feb. 18, 1928 2 Sheets-Sheet 2 IIIIJIIIIIIIIII 11",

wuemtoz gwdb 23% hlumww Patented A r. 28, 1931 UNITED STATES PATENT OFFICE- LBE DE FOREST, 0! NEW YORK, N. Y., ASSIGNOR T0 DE FOREST PHONOFILM CORPORA- TION, OF NEW YORK, N. Y., A GORPORATIQN OF DELAWARE AUTOMATIC PHQTOGRAPHIC SOUND-REPRODUCING MECHANISM Application tiled February 18, 1928. Serial No. 255,397.

This invention relates in general to mechanism for reproducing sounds from photographic sound records.

One of the objects of this invention is the a provision of apparatus of this general type characterized by the fact that it employs a photographic film having a plurality of sound records thereon.

A further object of this invention is the 3.0 provision of apparatus of the above type adapted to automatically move the film therethrough in one direction and reverse the direction of movement to move the film back through the machine in the other direction so that the film passes through the machine as many times as there areseparate photographic records on the film;

A further object of this invention. is the provision in apparatus of the above type of a unitary structure for supporting a light source and a light slit so that the structure may be moved to bring the slit in alignment with each sound record in succession as the film travels backwards and forwards through the machine.

A still further object of this invention is the provision of mechanism controlled by the movement of the film itself for efiecting the reversal of the driving means which moves the film.

A still further object of this invention is the provision of a plurality of light apertures arranged side by side sothat the light from the light source may successively be transmitted through each of the sound records seriatim to a light sensitive device.

A still furtherv object of this invention is the provision of mechanism likewise con-' trolled by the movement of the film for sucthe provision of mechanism of the above type all mounted on and within a container so by means of a unitary apparatus.

These and other objects as will appear from the following disclosure as secured by means of this invention.

This invention resides substantially in the cessively exposingz each sound record to the that all of the above objects may besecured combination, construction, arrangement, relative location of parts and circuital connec tion, all as will more fully appear in the detailed disclosure below.

Referring to the drawings in which the same reference numerals are used to indicate the same or similar parts in the diflerent views- Figure 1 is a diagrammatic illustration of the apparatus employing the principles of this invention;

Fig. 2 is aside vertical cross sectional view through the container ofthe mechanism showing various parts in side elevation;

Fig. 3 is anienlarged side elevational view of the unitary light source devices and the light sensitive cell;

. Fig. 4 is across sectional view taken on the line 4-4 of Fig. 2 showing a detail of construction Fig. 5 is a vertical cross sectional view tak en on the line 5 5 of Fig. 4;

Fig. 6 is an enlarged side elevational view of the escapement mechanism employed for moving the unitary light source and slit mechanism step by step; and

Fig. '7 is an enlarged detail view showing the plurality of aligned light apertures.

This invention relates to improvements in phonofilm or sound reproducing apparatus adapted to the purpose ofreproducing sound without reference to any motion picture on the film for use in legitimate theaters, restaurants, dance halls, and the like or in the production of incidental music accompanyin g motion pictures with which it is not necessary to synchronize the sounds; also in connection with amplifiers at radio broadcasting stations, etc.

The fundamental idea underlying the invention is to em loy a photographic film such as the type or inarily employed in motion picture work having thereon a plurality of individual and separate 'sound records arranged parallel and longitudinal of the film strip. The apparatus employed therewith is eonstructed so as to automatically cause the movement of the film therethrough to reproduce sounds from the photographic sound records thereon in succession.

In order to .'s'e

sound records 3, 4, 5 and 6. It is to be understood, of course, that as many sound records as is practical may be employed on the film. As shown in this figure, however, each sound record is approximately one-quarter of an inch in width. which is somewhat greater than the width of sound records employed on film having also a picture record thereon. When sound records of this width are used the ratio between the recorded sound and the ground noise, due to graininess of the emulsion, is.

much larger so that it is easier to reproduce the sounds without any traces of ground noise, scratching, and the like. The invention, of course, is not to be limited in any way by the width of the sound record employed. The film as shown is intended to represent the full length of film employed. In order to prevent the film running entirely through the machine before a reversal of the film can be effected after a complete sound record has been run off it is necessary to provide fairly long leads or lengths on each side of the sound records which have been indicated b A and B. It may also be pointed out here that the sound records can be, and generally will be, of different lengths, the only effect of this being that the time between the sound reproductions from the different records will be different. The film is provided a short distance on each side of the endsof the sound records with notches 7-and 8. -Mounted adjacent the film so as to be in contact with the edges thereof are the two spring fingers 9 and 10 provided with the contacts 11 and 13. A stationary contact 12 is mounted adjacent the contact 11 so that when the spring finger 9 is in the notch 7 the two contacts 11 and 12 will be closed. Similarly a fixed contact 14 is mounted adjacent the contact 13. A wire 15 joins the two fingers 9 and 10 together electrically. A wire 16 extends from the fixed contact 12 to one terminal of the electromagnet 17 and the wire 19 connects the fixed contact 14 with one terminal of theelectromagnet 18. These two electromagnets are connected together in series and a lead 21 connects the wire joining the two magnets to one side of the current source 20, the other side of which is connected through the wire to the wire 15. i

Mounted on a pivot pin adjacent the electromagnets so that one end thereof can oscillate between their cores is. a lever having The film isa U-shaped end forming part of an escapenient mechanism. Mounted on the lever 22 and electrically in contact therewith are the two contacts 23 and 24' arranged so that in one position of the lever the contact 23 will touch the fixed contact 25 and in the other position the contact 24 will touch the fixed contact 26. Contact26 is connected by means of the wire 27 to one side of the power source. Contact 25 is connected by means of the wire 28 to another terminal of the power source. The pivoted lever 22 is connected by the wire 29 to a fixed contact 30 which is arranged to make contact with another contact 31. Con tact 31 is mounted on and connected by a spring finger 91 to movable contact 32 which is adjacent the fixed contact 33 connected to the wire 28. The wire 34 connects the contacts 31 and 32 with the field winding 35 of the motor 65 (Fig. 2) which operates the mechanism. .The field winding 35 is in series with another fieldwinding 36 which is connected by means of the wire. 37 to the power source. As illustrated here, it is intended to drive the motor 65 from a three-wire current source, as for instance a three-wire direct current source, but it is, of course, apparent that those skilled in the art may devise many other means for effecting the reversal of the motor. As indicated in Fig. 1, the wire 37 represents the neutral wire. The contacts 31 and 32 are mounted on a pivot or spring lever. as will be described in connection with Fig. 6.

A physical embodiment of mechanism illustrated diagrammatically in Fig. 1 will now be described in connection with the other figures. In Fig. 2 the mechanism is shown within a suitable closed container 38 provided at the top and bottom with film magazines 39 and 40 of the type usually employed in connection with motion picture film. The film 1 is threaded from the upper magazine 39 between rollers above an opening in'the top of the case which provides the usual fire gate down over the sprocket wheel 41 mounted on the shaft 42,. Exterior of the casing and mounted on. the shaft 42 is a pulley 43 which is connected throu h a suitable belt 44 to a pulley, not shown {this is the usual construction), for driving the spool on which the film is wound. The film then passes around the smooth roller 46 and is held tight by means of the pivoted gravity roller 45. The roller 45 is mounted on the same shaft with a relatively heavy flywheel 47 for rotation therewith. The shaft on which the roller 46 and the flywheel 47 are mounted may be jour- I nalled in the sides-of the casing or otherwise suitably supported for rotation. The film is held into close frictional engagement with the roller 46 by means of the pivoted arms 48 having rollers on their ends and held against the film by means of the tension spring 49. The film then passes down beto the roller46. and thence to the sprocket wheel 56 mounted on the shaft 58.

The roller 42 is mounted on the same shaft as the flywheel 53 for rotation therewith. As before, the film is held in contact with the roller 42 by means of the pivoted arms .54 drawn together by means of the tension spring 55. The film in passing from the roller 52 to the sprocket 56 is under the action of the pivoted gravity lever 55. The film, after passing overthe sprocket 56, goes through an opening in the bottom of the case and two rollers and is finally wound up on a spool in the ma azine 40. On the same shaft with the sproc et 56 is a pulley 59 which drivesthe spool in the casing 40 by means of the belt 57 and another pulley, not shown. The shaft 58 is driven directly by means of the motor 65, sprocket wheel 66, sprocket chains and sprocket wheel on the shaft 58. Mounted on the shaft 58, as will be apparent from Fig. 4, is a worm wheel 68 which drives through the agency of the worms 67 .on each end of the shaft 60 the other shaft 42 which is provided with a worm wheel similar to the worm wheel 68. A clear understanding of the arrangement of the sprocket wheels, pulleys, and worm wheel may be secured from Figs. 4 and 5.

It may be pointed out here that the toothless rollers and the flywheels which are employed for imparting steady continuous movement of the film past the light source form the subject matter of the copending applications of Lee de Forest for device for feeding film in recording and reproducing apparatus, Serial No. 101,068, filed April 10th, 1926, and Richard R. Halpenny for propelling mechanism, Serial No. 210,795, filed August 5th, 1927.

Referring to Fig. 3 which shows in detail the construction of the light source, lens system, slit block and light sensitive cell unit the film'is shown as before at 1 passing down between the block 51 having the light apertunes therein and the block 71 supporting the light source, lens system and slit block elements. The block 51 is provided with the usual spring shoes 72 for holding the film in engagement with the slit block. The block 51 is mounted on the tube 73 which forms a sliding fit for the cylindrical extension 75 on the casing 7 4 within which the light sensitive or photoelectric cell 77 is mounted. The casing 74 is supported in any suitable manner and is stationary. A spring 76 encircling the cylindrical extension 73 is held under compression and tends to force the block 51 and the spring shoes 72 to the left to hold the film 71 against the light aperture block 71. As shown in Fig. 7 the light aperture "block 71 is supported on the casing and is with two mitered strips 85 which form tracks on which the slit block 84 may be slidably mounted. The casing 62 supported on the brackets 63 provides a housing for the constant light source 80, which light. source is provided with the wires 79 for supplying current thereto. Formed on the casing 62 is a tubular extension 79 provided with a lens system comprising the lenses 80 and 82 and a light aperture 81. The tubular extension 79 is supported by means pf the brackets 63 which may be partially supported and guided by means of a rod extending through the hole 88, which rod may be suitably supported at its ends. The rod forms a sliding fit with the brackets 63 so that it may slide therewith. Secured to the tubular extension 79 for movement therewith is a plate 83 which is secured by another tubular extension to the'light slit block 84.

The mechanism for giving a step by step movement to the unitary structure comprising the light source, the lens system, and the slit block is shown in Fig. 6. The lower edge of the plate 83 is rovided with a series of teeth 86. The slit lock 84 is shown in front of the plate 83 and is provided with any suitable means for providing a fine slit 85 through which the light from the light source may be transmitted to the particular sound record in front of the slit. The plate 83 and all of the mechanism attached thereto is urged to the right (Fig. 6) by means of a tension spring 87 secured to the casing. Mounted in the path of the plate is the spring finger 91 on which are formed the two contacts 31 and 32. The contact 32 cooperates with the contact 33 supported upon the post 88 attached to the casing and insulated therefrom. The escapement mechanism for giving a step by step movement to the plate 83 and the parts supported thereby under the action of the spring 87 is'shown comprising shaped cores 92 and 93 respectively. A

spring 110 suitably supported is arranged in the path of the oscillating lever 22 so that the lever tends to lie on either side of the spring until urged to the other side by means of the proper magnet. As the lever oscillates back and. forth under the influence of the magnets 17 and 18 the plate 83 is premitted to move to the right one step at-atime. As a result of this movement the slit block having the light slit 85 is moved successively into alignment with the light apertures 98 so that the light source which moves with the slit may transmit light rays through by means of wires 78 to a vacuum tube amplifier 101 mounted in the casing 100 attached to the casing 38. The wires 102 leading from the vacuum tube amplifier are connected to additional stages of audion amplifiers or to sound reproducing device as found suitable.

The description of the operation of the apparatus will now be given. The film containing the sound records is mounted on-a suitable spool within the magazine 39 and threaded over the various sprockets and rollers as previously described. For the first run of the film through the machine the plate 83 and the mechanism supported thereby will be in the extreme position at the left, as shown in Fig. 6, so that the light slit 85 is in alignment with the light aperture 98 through which the sound record 3 can be viewed. The current is then supplied to the motor 65 by closing any suitable form of switch and the fihn runs through the meehanism reproducing the sounds from the sound record 3. It is assumed ,in this description that the film in its first run through the machine is moving in the direction indicated by the arrow in Fig. 1. When the record has been completely reproduced the film is moved so that the spring finger 10 drops into the notch 8 in the film. As a result the following circuit is completed. Fro-m one side of the current source 20 through wire 20, wire 15, finger 10, contacts 13 and 14, wire 19, electromagnet 18 and back to the current source through the wire 21. As a result the magnet 18 is energized and the pivoted escapcment lever 22 moves to the right (Fig. 1) and, as

' a result, the current which was formerly flowing from wire 27 through contacts 26 and 24, lever 22, wire 29, contacts 30 and 31, Wire 34, field windings and 36 back to the current source through wire 37 is reversed so that it now flows from the current source through wire 37, field windings 36 and 35, wire 34, contacts 31 and 30, wire 29, lever 22, contacts 23 and 25, and thence to the current source through wire 28. As a result the film is caused to travel back through the machine in the reverse direction. Themovement of lever 22 from one position to the other permits the movement of a unit comprising the light source, the lens system, the plate 83 and the slit block 84 to move one step to the right (Fig. 6 so that the slit 85 is. now in alignment with thatlight aperture through which the sound record 4 may be seen (Fig.7). The sounds represented by the sound record 4 are, therefore, reproduced. When the record has been completely reproduced spring finger 9 falls into notch 7 so as to complete a circuit, as follows, to energize the electromagnet 17 from one side of the current source 20 through wire 20', wire 15,

s ring finger 9, contacts .11 and 12, wire 16, e ectromagnet 17 and back to the current source 21. This causes" an energization of the electromagnet 17 and moves the escapement lever 22 back to the left to effect a sec- 0nd reversal of the current through the motor as well as causing the light slit 85 to move in alignment with the third sound record 5. The film then reverses and runs through the machine causing reproduction of the sounds 87 moves the plate 83 to the right so that the end thereof contacts with the spring finger 91 (Fig. 6). This completes a circuit between the contacts 32 and 33 and breaks the circuit between contacts 31 and 30 so that the motor continues to operate to finish winding up the film so that the reel may be removed from the magazine. It is,- of course, understood that the film is provided with a lead at each end-A and B-of suflicient length so that it will not completely 'run through the machine during the operations of reversing the motor and moving the light slit. To reset the device the unitary structure mounted on the brackets 63 and plate 83 are moved by means of the finger ring 95 to the left (Fig. 6) so that the first tooth on the plate again engages with the lever 22. It is, of course, undersood that thealternate sound records are recorded on the film in reverse order in order to effect the movement of the sound record past the light source in the proper direction. It will be apparent that the film is run past the light slit as many times as there are sound records thereon and it is likewise apparent that the number of sound records on the film need not be limited to four as shown for purposes of illustration.

The purpose of the smooth rollers 46 and 42 and their flywheels is to impart a perfectly smooth and continuous motion to the film by virtue of the inertia of the heavy flywheel. In view of the fact that the film runs through the machine in both directions it has been found that it is advantageous to employ one of these smooth rollers and flywheel units on each side of the light slit structure so that the film will run smoothly therepast in either of its directions of movement; The use of such inertia rollers in connection with gravity tension levers was proposed as disclosed in to employ two such inertia rollers, one located on either side of the slit block. While one thereof isnot absolutely essential and there are other equivalents in the art which may be substituted therefor I find that they are advantageous in securing perfect motion of the film past the slit block in either direction.

It may be pointed out that the photoelectric cell 77 must be suificiently large so that its cathode surfaceis illuminated by the light falling through any one of the windows 98. The members 81 in the light tube 79 provide a masking plate so that no light can enter through the slit block 84 except through whichever window 98 the slit 85 happens to be in front of. It may also be pointed out that a single long window may be formed in block 71 in place of the four separate windows shown for purposes of illustration.

From the foregoing disclosure it will be apparent that if the strip of film is two thousand feet in length, for instance, and carries four sound records it will have an effective sound reproducing length of eight thousand feet sothat if the film is run through the machine at the rate of eighty feet per minute there will result a sound reproduction for the durationof one hundred minutes without requiring any attention on the part of the operator. There is, of course, a slight delay at each reversal of the film during which time the motor is; reversing and the film getting up again to normal speed. It is desirable, therefore, that each sound record 3, 4:, 5 and 6 comprise a complete musical or spoken numher. This frequently means that one record may be very much longer in length than one of the records next to it but this only means a longer time interval between the termination of the reproduction of one record and the beginning of the reproduction of the next.

It will be apparent from the foregoing disclosure that I have devised a newand novel combination of elements which employ particular principles of operation which may be embodied in many other practical forms by those skilled in this art. It is obvious that many other types of automatic film reversing and driving mechanisms may be employed and also different mechanical arrangements for propelling the slit carrying block right or left to the required position for the next reco'rd. Since it is obvious, therefore, that 'many changes may be made in the details of construction and relative arrangement of parts I do not wish to be limited to the exact disclosure given for purposes of illustration but rather to the invention as it is defined in the appended claims; For example, instead of providing automatic means for causing the motor to continue to operate to wind up the film on one reel at the end of the last record it is apparent that. a manually operated switch can beemployed.

ers, means for reversing the direction of thefilm past the slit block and over the rollers, and means to move said slit block when the film direction means are actuated.

2. In a mechanism for reproducing sounds from photographic records on a film, the combination with a light source, a slit block adapted to movement transverse to the film and a light sensitive device, of means for antomatically causing the movement of the film successively past the slit block in opposite directions, and moving said slit block on each glliange in the direction of motion of the 3. In a photographic sound reproducing device employing a photographic film having a plurality of sound records thereon, the combination with a light source, a movable slit block and a light sensitive device, of means for moving the film past the slit block in alternate directions, means for imparting steady movement to the film as it passes the slit block in either direction, and means to move said slit block transversely of the film glll each change in direction of motion of the 4. In a mechanism for reproducing sounds from a film having a plurality of sound records thereon, the combination with a movable slit block of means for automatically causing the film to move past the slit block successively in opposite directions, and means for moving the slit block to align the same iiiccessively' with each sound record on the 5. In a sound reproducing device, the combination of a casing, a film magazine mounted on the top of the casing, a film magazine mounted on the bottom of the casing, a movable slit block within said casing, power operated means for moving the film past the light slit from one magazine to the other successively in opposite directions, and electromagnetic means for moving the slit block .upon each reversal indirection of the film.

6. In a soundreproducing device for the exposed to the light source as the film moves past the slit block in opposite directions.

7. The combination with a movable slit block in a sound reproducing mechanism employing a photographic film of an interior roller mounted on each side of the movable slit block over which the film passes and gravity actuated means for imparting uniform tension to the film, means to cause the film to alternately move smoothly past the slit block in opposite directions, and means to move the slit block when the last mentioned means are actuated.

8. In a sound reproducing device employing a photographic film having a plurality of sound records thereon, the combination with a movable slit block of means for moving the film past said slit block successively in opposite directions andmeans for moving the slit block transversely of the film on each reversal of the film to align the slit with the proper record on the film.

9. In a sound reproducing device employing a photographic film having a plurality of parallel sound records arranged longitudinallyof the film, the combination with a slit block havinga fine slit therein and means for moving the slit block step by step in a direction transverse to the direction of movement of the film of means for propelling past the slit block in either direction and means for reversing the propelling means at the end of the reproduction of each record.

10. In a sound reproducing device employing a photographic film having a plurality of parallel sound records arranged longitudinally of the film, the combination with a slit block having a'fine slit therein and means for moving the-slit block step by step in a direction transverse to the direction'of movement of the film of means for propelling past the slit block in either direction and means for reversing the propelling means" at the end of the reproduction of each record and for causing theslit block to move transversely one step at a time to align the slit with each sound record in succession.

11. In a sound reproducing device employing a photographic film having a plurality of sound records arranged longitudinally of the film, a slit block arranged for movement transversely of the path of movement of the film and electromagnetic means for moving said slit block in a step by step movement.

12. In a sound reproducing device employing a photographic film having a plurality of sound records arranged longitudinally of the film, a slit block arranged for movement transversely of the path of movementot the film and electromagnetic means for moving said slit block in a step by step movement, and means associated with the film for controlling said electromagnetic means.

13. In a sound reproducing device employing a photographic film having a plurality of sound records arranged longitudinally of the film, a unitary structure comprising a light source and a slit block arranged to be moved transversely of the path of the film, means for moving the film past the slit block alternately in opposite directions, means for controlling said means for effecting the alternate movement of the film, means'for imparting step by step movement to said unitary structure, and means operated by the means for imparting step by step movement to the unitary struclure or causing said means for moving the film past the slit block to continue the movement of the film past the slit block at the end of the reproduction of the last record until all the film has passed the slit block.

14. The combination with a photographic film having a plurality of sound records thereon, of a slit block having a fine slit adapted to move transversely of the film and means to move the film past the slit block alternately in opposite directions and to move the slit block step by step to bring the slit successively in alignment with each sound record on the film.-

15. The structure substantially set forth ill-Claim 13 characterized in this, namely that rotatable means are mounted adjacent to and on each side of the slit block for imparting steady movement to the film as it passes the slit block in either direction.

16. The structure substantially set forth in claim 13 characterized in this, namely that a rotatable roller and flywheel are mounted on each side of the slit block so that the film passes over each roller in its movement past the slit block, and means for resiliently causing the frictional engagement with the rollers.

17. The structure substantially set forth in claim 13 characterized in this, namely that there is mounted on each side of the slit block an interior roller over which the film passes, and gravity actuated means for imparting uniform tension to the film whereby the film moves smoothly past said slit block in either direction.

18. The combination with a notched photographic film having thereon a plurality of sound records, of a plurality of spring fingers arranged to engage the notched film as it moves past said fingers, a slit block adapted to step by'step transverse movement with respect to said film to cause the slit thereon to register successively with the records on '1 19. The combination with a notched photogra hic 'film having thereon a plurality of soun records, of a plurality of spring fingers arranged to engage the notched film as it moves pastsaid fingers, a slit block adapted to step by step transverse movement with respect to said film to cause the slit thereon to register successively with the records on the fihn, means to reverse the direction of movement of the as the spring fingers engage with the notched film and to move the slit block one corresponding step, and means whereby the last step movement of the slit block after reproduction of the last sound record closes a circuit cutting out the step by step actuation of the slit block and actuates means to complete the winding up of the film.

20. The combination with a notched photographic film, of a plurality of spring finzo gers arranged to engage the notched film as it moves past said fingers, and an electric motor for moving said film in either direction, of electromagnetic means for reversing the direction of rotation of said motor by reversing the connections thereto, circuit connections 'between said fingers and said reversing means, a slit block adapted to step by step movement transverse to the film, means to actuate said slit block to move a corresponding step for each reversal in direction of rotation of said motor, and means whereby the taking of the last step in the movement of said slit block cuts out the actuating means and closes the circuit to the motor to cause the same to complete the winding up of the film.

In. testimony whereof I have hereunto set my hand on this 15th day of February, A. D. 1928.

4o LEE on FOREST. 

